Method and apparatus for aligning a knee for surgery or the like

ABSTRACT

Generally described the invention relates to methods and apparatuses for aligning the lower extremities of a patient with a mechanical axis. More specifically, the present invention provides an exoskeleton or external framework that positions a patient&#39;s leg into a desired mechanical axis in preparation for surgery or other medical treatment.

CROSS REFERENCE SECTION

This application claims the benefit and priority of U.S. ProvisionalApplication No. 60/552,641, filed Mar. 11, 2004, which is incorporatedherein in its entirety.

FIELD OF THE INVENTION

The present invention is generally related to the manipulation of a legto provide surgery thereon or other medical attention thereto. Morespecifically, the present invention provides an external frame, or“exoskeleton” to position the leg into a desired axis in preparation forsurgery or other treatment on the knee.

2. Background of the Invention

Damage to the weight-bearing surfaces of the knee as a result ofarthritis and/or trauma can be isolated to one compartment, or can beglobal (involving two or more of the three compartments of the knee).The three compartments of the knee are the patellofemoral compartment,the medial compartment and the lateral compartment. When damage to theknee results in a change in the shape of the underlying bone of theknee, the damage is permanent. Surface replacement procedures such as atotal knee arthroplasty (TKA) and a unicompartmental knee arthroplasty(UKA) are typical corrective measures for this damage.

The natural biomechanics of the knee places the weight-bearing axis in aposition to allow approximately 60% of the weight bearing by the medialcompartment and 40% by the lateral compartment of the knee. Thisweight-bearing axis is measured in the frontal plane and is a line drawnfrom the center of the femoral head to the center of the ankle.Therefore, this line must fall slightly to the medial side of the centerof the knee to accomplish this weight-bearing distribution. Loaddistribution across the knee corresponds to the relative surface area ofeach compartment. That is to say, the medial compartment is generally60% of the total bearing surface area of the knee. The body distributesthis weight optimally to maintain a certain amount of load per squareinch of surface area. When this load exceeds a certain level in one orthe other compartment, overload in that compartment occurs and damageensues. The damage begins with articular cartilage wear and can progressto flattening of the condyle with its resultant shape change in thecondyle.

When only one compartment in the knee has been damaged permanently, aunicompartmental knee arthroplasty or UKA is used to replace the damagedbone surface. This type of prosthesis has several common failuremodes: 1) the side with the UKA fails due to poly wear or interfacefailure; 2) the opposite compartment fails due to a substantial increasein arthritis; and 3) the femoral component impinges on the patellacreating an impingement syndrome. Each of these failures can beattributed to misalignment of the implant. Therefore, there is greatneed when performing a UKA to implant the device such that the propermechanical axis within the knee is recreated. Since every lowerextremity is unique, the mechanical axis must be uniquely reproduced forthe best chance at long-term success. When installed in alignment withthe proper axis, the UKA survival rate is greatly improved.

Total Knee Arthroplasty or TKA is a surgical procedure wherein both thelateral and medial compartments are replaced. The proper mechanical axisfor these procedures is also important to the long-term success of theimplant.

Several prior art devices have been used for the purpose of establishingan axis for partial and total knee replacement surgery. One procedureinvolves forcing a metal rod into the end of the thighbone. The surgeonthen uses this rod to estimate the proper angle for cutting the bone andinstalling the prosthesis. This procedure has numerous disadvantagesincluding inaccurate cutting of the bone resulting in incorrectplacement of the prosthesis and blood clots that may occur from forcingthe rod into the marrow of the thighbone to estimate the mechanicalaxis.

An additional method for aligning the bones for a knee replacementsurgery is a device called an intramedullary guidance system. Thisdevice takes measurements of the leg and calculates the properalignment. However, the measurements tend to be inaccurate because theyare taken from the somewhat deformable tissue covering the bone ratherthan the more rigid bone itself. As a result, the alignment measurementsvary based on the amount of tissue covering the bone.

Once the axis is estimated using one of the techniques described above,a cutting guide is secured to the bone, which requires multipleincisions. The securing process may weaken the bone and increase therecovery time.

An additional factor in the placement of a knee prosthesis is thenatural amount of ‘play’ in the joint. This ‘play’ is defined as thenatural amount of motion between the two bones of the joint allowed bythe ligaments. In a knee joint with a lot of “play,” incongruous jointsurfaces will still allow full flexion and extension. On the other hand,a knee joint with very little ‘play’ must have perfectly shaped jointsurfaces to allow full flexion and extension. One job of the surgeonduring implantation of either a TKA or a UKA is the need to recreate thepatient's normal amount of joint ‘play’. This means the appropriateamount of ligament release and implant size must be used to allow forboth the appropriate amount of ‘play’ and correction of the mechanicalaxis. The current known methods do not provide a method of determiningthe natural play of a joint.

Therefore there is a need for methods and apparatuses for the alignmentof a leg for surgery or other medical attention that addressdeficiencies in the art, some of which are discussed above.

SUMMARY OF THE INVENTION

The present invention provides improvements over the prior art byproviding a method and apparatus for aligning a leg in order tofacilitate surgery or medical treatment thereon.

Therefore it is an object of the present invention to provide animproved medial device and technique of using same.

It is a further object of the present invention to provide an improvedmethod and apparatus for aligning a knee joint of a patient.

It is a further object of the present invention to provide an improvedmethod and apparatus for aligning a knee of a patient for the purposesof knee replacement surgery.

It is a further object of the present invention to provide an improvedmethod and apparatus for assessing the natural play associated with aknee joint.

It is a further object of the present invention to provide an improvedmethod and apparatus for aligning the knee while in a bent condition.

It is a further object of the present invention to provide a method andapparatus to increase the speed of knee replacement surgery.

It is a further object of the present invention to provide an improvedmethod and apparatus to reduce the number of persons required to performa UKA or TKA.

It is a further object of the present invention to provide an improvedmethod and apparatus to reduce the need for drilling into bone to securecutting guides during knee replacement surgery.

It is a further object of the present invention to provide an inflatablebladder under the thigh to provide distraction of the knee joint whenthe leg is in the bent or flexion position.

In an aspect of the present invention, an apparatus is provided foridentifying the mechanical axis of a leg of a patient to facilitatemedical treatment thereon, the leg including a femoral head, and a footportion which itself includes an ankle portion, the mechanical axishaving a portion extending from the center of the femoral head to thecenter of the ankle, the apparatus including a base member including aspine portion and a head portion, the spine portion being substantiallyelongate and having a longitudinal axis, the head portion attachedproximate one longitudinal end of the spine portion, a pelvic locationassembly attached relative to the base member proximate the headportion, the pelvic location assembly including a femoral head locationmember configured to identify the approximate location the femoral headof the leg, the pelvic location assembly also configured to establish afirst reference point positioned at a known location relative to thecenter of the femoral head, a carriage moveably attached relative to thespine portion and configured to be moved along a carriage path having aportion being substantially parallel to the longitudinal axis of thespine, and the carriage further configured to be selectively securedrelative to the spine so as to discourage the relative movement betweenthe carriage and the spine, a boot assembly pivotably attached relativeto the carriage and configured to accept the foot portion of the leg andto establish a second reference point at a known location relative tothe center of the ankle portion, and a mechanical axis indicatorproviding a visual indication of a portion of a reference axis passingthrough from the first reference point and through to the secondreference point, the reference axis being within substantially the sameplane as the mechanical axis.

In a further aspect of the present invention, an apparatus is providedfor aligning a leg of a patient with a mechanical axis to facilitatemedical treatment thereon, the leg including a femoral head, a thighportion and a foot portion which itself includes an ankle portion, themechanical axis having a portion extending from the center of thefemoral head to the center of the ankle, the apparatus including a basemember including a spine portion and a head portion, the spine portionbeing substantially elongate and having a longitudinal axis, the headportion attached proximate one longitudinal end of the spine portion, apelvic location assembly attached relative to the base member proximatethe head portion, the pelvic location assembly including a femoral headlocation member configured to identify the approximate location thefemoral head of the leg, the pelvic location assembly also configured toestablish a first reference point positioned at a known locationrelative to the center of the femoral head, a carriage moveably attachedrelative to the spine portion, and configured to be moved along acarriage path having a portion being substantially parallel to thelongitudinal axis of the spine, the carriage further configured to beselectively secured relative to the spine so as to discourage therelative movement between the carriage and the spine, a boot assemblypivotably attached relative to the carriage and configured to accept thefoot portion of the leg and to establish a second reference point at aknown location relative to the center of the ankle portion, a mechanicalaxis indicator providing a visual indication of a portion of a referenceaxis passing through from the first reference point and through to thesecond reference point, such that the reference axis is withinsubstantially the same plane as the mechanical axis, a leg manipulationassembly attached relative to the spine portion between the pelviclocation assembly and the boot assembly, the leg manipulating assemblyhaving a first lateral force assembly and a second lateral forceassembly the force assemblies being proximate the thigh portion andspaced apart to accept the leg therebetween and located proximate theknee joint, the first lateral force assembly being adjustable andselectably securable along an axis substantially perpendicular to thelongitudinal axis of the spine and configured to discourage the leg frommoving away from a desired alignment with the mechanical axisidentifier.

In another aspect of the present invention, an apparatus is provided foraligning a leg of a patient with a mechanical axis to facilitate medicaltreatment thereon, the leg including a femoral head, a thigh portion, aknee portion and a foot portion which itself includes an ankle portion,the mechanical axis having a portion extending from the center of thefemoral head to the center of the ankle, the apparatus including a basemember including a spine portion and a head portion, the spine portionbeing substantially elongate and having a longitudinal axis, the headportion attached proximate one longitudinal end of the spine portion, apelvic location assembly attached relative to the base member proximatethe head portion, the pelvic location assembly including a femoral headlocation member configured to establish a first reference pointpositioned at a known location relative to the center of the femoralhead, a carriage moveably attached relative to the spine portion andconfigured to move along a carriage path having a portion beingsubstantially parallel to the longitudinal axis of the spine and furtherconfigured to be selectively secured relative to the spine so as todiscourage the movement, a boot assembly pivotably attached relative tothe carriage and configured to accept the foot portion of the leg and toestablish a second reference point at a known location relative to thecenter of the ankle portion, a upper pivoting assembly having a firstend pivotably attached relative to the spine portion proximate the headportion, a second end pivotably and moveably attached relative to thespine portion and a hinged portion positioned proximate the patient'sknee between said first end and said second end such that when saidpatient's knee is in a bent condition, said second end moves relative tosaid spine portion and said hinge portion follows said knee such thatsaid thigh support member also provides support to said thigh portion ofsaid leg, a mechanical axis indicator providing a visual indication of areference axis passing through said first reference point and throughthe second reference point, such that the reference axis is withinsubstantially the same plane as the mechanical axis, and a legmanipulation assembly attached relative to the spine portion between thepelvic location assembly and the boot assembly, the manipulatingassembly having a first lateral force assembly and a second lateralforce assembly being spaced apart to accept the leg therebetween andlocated proximate the knee joint, the first lateral force assembly beingadjustable and selectably securable in an axis substantiallyperpendicular to the longitudinal axis of the spine and configured tourge the leg into alignment with the mechanical axis identifier.

In a further embodiment of the present invention, an apparatus isprovided that is configured to measure the clearance between the matingsurfaces of the femur and a tibia at the knee joint, the apparatus beingelongate with a substantially wedge shaped tip portion, the wedgedshaped tip portion including indicia associated with a width at adistance spaced apart from the end of the wedge shaped tip.

It is to be understood that the inventions are not to be limited to thespecific embodiments disclosed and that modifications and otherembodiments are intended to be included within the scope of the presentinvention. Although specific terms are employed herein, they are used ina generic and descriptive sense only and not for purposes of limitation.

Other objects, features, and advantages of the present invention willbecome apparent upon reading the following detailed description of thepreferred embodiment of the invention when taken in conjunction with thedrawing and the appended claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates certain bones in a typical human leg. As may be seen,the femur 2 extends from a pelvis 9, to a knee joint. A tibia 3 extendsfrom the knee joint to an ankle (not shown). The mechanical axis (MA) iscreated by a line running through the femoral head and the center of theankle 4.

FIGS. 2A and 2B are other illustrative views of a leg of a patient and aportion of an embodiment of the present invention. This view may beconsidered a side plan view of a patient in a prone position and lookingat the patient from the patient's right side.

FIGS. 3A, B is an illustrative views of a portion (from the waist down)of a patient and a portion of an embodiment of the present invention.This view may be considered a top plan view of a patient in the proneposition, looking down from above the operating table the patient islying on.

FIG. 4 is a simplified drawing of a portion of apparatus 10 inaccordance with one embodiment of the present invention.

FIG. 5 is a drawing of apparatus 10 shown in an extended configurationin accordance with an embodiment of the present invention.

FIG. 6 is a drawing of the pelvic location assembly 30 according to thepresent invention.

FIG. 7 is a drawing of a portion of the pelvic location assembly 30showing the alignment line assembly 40 in accordance with one embodimentof the present invention.

FIG. 8 is a drawing of a portion of the apparatus 10 focusing on theupper pivoting assembly 50 in accordance with an embodiment of thepresent invention.

FIG. 9 is a drawing of a portion of the apparatus 10 focusing on thelower pivoting member 80 in accordance with an embodiment of the presentinvention.

FIG. 10 is a drawing of a portion of the apparatus 10 focusing on thesupport column 70 and the cutting guide mounting assembly 71 inaccordance with an embodiment of the present invention.

FIG. 11 is another view showing the cutting guide mounting assembly 71similar to FIG. 10, but shows the cutting guide mounting assembly 71 inan extended state.

FIG. 12 is a drawing of the foot cradle assembly 136 without thecarriage 90 in accordance with one embodiment of the present invention.

FIGS. 13A and 13B are drawings illustrating two embodiments of themeasurement tool 150 in accordance with the present invention.

FIG. 14 is a drawing of an embodiment of the bladder assembly 160 inaccordance with the present invention.

FIG. 15 is a flow diagram illustrating the steps of a method to align aleg in accordance with an embodiment of the present invention.

FIG. 16 is a drawing of a portion of a tibia 300 illustrating two cutlines for an osteotomy procedure.

FIGS. 17A and 17B illustrate cutting guides having slots therein inaccordance with an embodiment of the present invention.

FIG. 18 is a drawing of a tibia and a retention rod 330 in accordancewith an embodiment of the present invention.

FIG. 19 is a drawing of a retention rod in accordance with an embodimentof the present invention.

DETAILED DISCUSSION OF THE PRESENT EMBODIMENT

The present inventions now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, these inventions may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

General Construction and Operation

Generally described, the invention relates to a method and apparatus formanipulating a human leg into a desired alignment in preparation forsurgery or other medical treatment. Referring generally to FIG. 1, themechanical axis MA of a patient's leg is created by a line stretchingfrom the femoral head 1 of the femur 2 to the center of the ankle 4. Ina preferred embodiment, an external framework, or “exoskeleton” providesa visual indication of a reference axis which is within the samevertical plane as the proper mechanical axis MA. This framework alsoprovides a means for manipulating the patient's leg into a desiredalignment with the visual indication.

Preferably, a patient's leg is aligned with its mechanical axis when thereference axis created by the present invention is positioned slightlyto the medial side of the patient's knee. This alignment achieves anoptimum weight distribution at the knee joint when the patient isstanding. However, as one of ordinary skill will appreciate, any desiredalignment with respect to the reference axis may be achieved using thepresent invention.

In addition to positioning the patient's leg into proper alignment, anembodiment of the present invention also provides an alignment featurefor surgical cutting guides. In this embodiment, a patient's leg and asurgeon's cutting guides are held in an optimal relative position by anexternal framework. In the prior systems, the leg is manually restrainedin its current position, which may or may not be the proper mechanicalaxis. The surgeon then estimates the adjustment angle necessary to placethe knee in its proper mechanical axis when the prosthesis is installedand adjusts the cutting guides accordingly. The success of the surgeryis directly related to estimate made by the surgeon, which is dependenton the skill and experience of the surgeon. With embodiments of thepresent invention, the surgeon no longer has to estimate the cut angleon the femur and tibia to achieve the proper mechanical axis MA tofacilitate proper installation of a knee prosthesis because the optimumangle is established by the external framework. Thus, the consistencyand accuracy of the cutting operation is improved with the use ofembodiments of the present invention.

Reference is now made to FIGS. 3A and 3B to further discuss the generaloperation of the invention. This figure shows a patient's legs in aprone position; the leg designated as 5 has a thigh portion 6, an ankleportion 7 and a foot portion 8. The preferred mechanical axis MA for thepatient's leg 5 is created by a line running through the femoral head 1and the center of the ankle 4. Because the femoral head 1 is notdetectable from outside the body, a skeletal reference point that isdetectable from outside the body is chosen to aid in locating thefemoral head 1. Preferably, the anterior superior iliac spine, which isthe bony prominence of the pelvis (i.e. edge of the pelvis 9), is chosenas the skeletal reference point. An X-ray of the patient is used todetermine the distance “d” from the skeletal reference point to thefemoral head 1. This distance “d” is used to approximate the location ofthe femoral head based on the skeletal reference point on the patient'sbody. A reference axis is then created using a cable, string, or laserthat is within the same plane as the mechanical axis MA which passesthrough the femoral head and the center of the ankle.

As best shown in FIG. 3A, the patient's leg 5 may not be in alignmentwith the mechanical axis MA prior to treatment. To place the leg inproper alignment, a force is applied in the direction of vector “F.”FIG. 3B illustrates an aspect of the present invention where an inflatedbladder creates a lateral force in the direction of vector F to urge theleg into alignment with the reference axis and therefore the preferredmechanical axis.

Turning to FIGS. 2A and 2B, a further aspect of the present invention isillustrated where the leg 5 of the patient may be bent without losingalignment with the mechanical axis MA. As illustrated, leg support isprovided by the external framework proximate the thigh portion of theleg thereby securing the knee in both the straight and bent positions.Additionally, an inflatable bladder may be positioned under the thigh toallow the surgeon to selectively distract the knee joint byinflating/deflating the bladder. These features allow the surgeon tobend the knee to a desired degree to provide access to the cut portionsof the tibia and femur as discussed in greater detail elsewhere in thisapplication.

When a surgeon is performing a partial knee replacement, it is importantthat the distance between the bearing surfaces of the femur 2 and thetibia 3 is consistent. Therefore, a surgeon measures the distancebetween the undamaged bearing surfaces of the knee and replicates thatdistance with the prosthesis. In an additional aspect of the presentinvention, a tool is provided for measuring this distance.

Referring to FIG. 13A, a measurement tool 150 is provided for measuringthe natural play in a knee joint. The measurement tool 150 is generallyelongate and has a wedge-shaped measuring portion 152 wherein indiciarepresenting the width of the wedge at different distances from the tipare provided.

In use, the leg of the patient is positioned in straight condition anddistracted by applying a force proximate the foot directed away from thepatient's torso. The detraction preferably extends the ligaments of theknee to their maximum length. The wedge-shaped measuring portion 152 ofthe measuring tool 150 is placed between the bearing surfaces of thefemur and tibia until the surfaces of the wedge contact both bearingsurfaces. The surgeon reads the indicia corresponding with the depth ofthe wedge to determine the distance between the bearing surfaces. Fromthis measurement, the surgeon can calculate the amount of bone to removeto achieve the same “play” with the prosthetic joint. FIG. 13Billustrates an alternative embodiment of the measurement tool 150 wherethe tool takes a more ergonomic shape.

More Detailed Discussion

Apparatus 10

The apparatus 10 is shown generally in FIGS. 4 and 5. This apparatus 10is used to manipulate a leg of a user (not shown) in order to providemedical attention thereto. Generally described, the apparatus 10includes a stationary base 20, a pelvic location assembly 30, a legmanipulation assembly 40, an upper pivoting assembly 50, a lowerpivoting member 80, a carriage 90, and a foot assembly 130.

Stationary Base 20

The stationary base 20 is configured to be positioned atop a stationary,substantially horizontal surface, which may be a floor, a suitablemedical table, or the like. This stationary base 20 is substantiallyrigid, and includes a planar head portion 21 fixed to a spine member 22.The planar head portion 21 is configured to support the posterior of apatient (not shown). Padding or the like may be positioned atop theplanar head portion as desired. The spine member 22 is essentiallyelongate, and is configured to accept various carriages to slide alongat least a portion of its length as discussed later in this application.

Pelvic Location Assembly 30

Turning to FIG. 6, the pelvic location assembly 30 is attached to theplanar portion 21 of the base 20, and is generally configured to providethe surgeon with a means for locating a point proximate the pelvicregion of the patient. The pelvic location assembly 30 is attached tothe base 20 on the side corresponding with the leg requiring treatmentusing locating pins 24 and fixing member 25. In the embodiment shown inFIG. 6, the pelvic location assembly 30 is attached to the right side ofthe base 20. But, as one of ordinary skill in the art will appreciate,the location assembly 30 may be positioned on the opposite side of thebase 20 as desired.

The vertical support member 32 of the pelvic location assembly 30 issubstantially elongate and has a vertical longitudinal axis. The lowerend of the vertical support member 32 is rigidly attached to thestationary base 20, although it may be removed and reattached to theother side as necessary. Proximate the upper end of the vertical supportmember 32 is attached an adjustable frame member 34. This adjustableframe member 34 is configured to be rigidly attached relative to thevertical support member 32, but also adjustable along a portion of itslength. Various members, including a skeletal reference location bar 36and an alignment line assembly 40 are supported by the vertical supportmember 34. A skeletal reference locator 38 is located at each end of theskeletal reference location bar 36. As discussed elsewhere in thisapplication, the skeletal reference locators 38 are configured tocontact a certain portion of the body directly above a skeletalreference point, such as the anterior superior iliac spine.

As shown in FIG. 7, the alignment line assembly 40 includes an elongatemember 41, an alignment reel 42, and an alignment line 43. The elongatemember 41 has one end pivotably attached relative to the adjustableframe member 34, and has its opposing end attached to and supporting thealignment reel 42 and associated alignment line 43.

As discussed in detail later, the alignment line 43 when extended isused to provide a visual indication of a reference axis that ispreferably substantially within the same vertical plane as themechanical axis of the leg requiring treatment. An X-ray is taken of thepatient and the distance between a skeletal reference point and thefemoral head 1 is determined. The location bar 36 is adjusted accordingto the determined distance using the scale positioned thereon. After thepatient is positioned in the apparatus with their skeletal referencepoint adjacent the reference locator 38, the alignment reel 42 will bepositioned proximate the center of the femoral head of the leg receivingtreatment. In other words, the skeletal reference locator 38 ispositioned a distance “d” from the alignment reel 42 using the scalelocated on the location bar 36.

Leg Manipulation Assembly 40

As shown in FIG. 5, the leg manipulation assembly 40 is configured toprovide at least two functions. One function is to allow for suitablealignment of the leg, and the second function is to allow the leg to bebent into a position for surgical treatment while maintaining alignment.Referring generally to FIG. 4, for example, the leg manipulationassembly 40 generally includes an upper pivoting assembly 50, a lowerpivoting member 80, and a carriage 90.

Upper Pivoting Assembly 50

Turning to FIG. 8, the upper pivoting assembly 50 is configured to bepivotably attached relative to the base 20 at pivot points P1. The upperpivoting assembly 50 is generally T-shaped. This member 50 includes apair of lower parallel frame elements 54, an upper frame element 56, aconnecting plate 58, a pair of length adjustment members 60 and atransverse member 62. The lower parallel frame elements 54 are eachsubstantially elongate and have parallel longitudinal axes. The upperframe element 56 is likewise substantially elongate and has alongitudinal axis substantial parallel to those of the lower parallelframe elements 54. The connecting plate 58 attaches to the upper ends ofthe lower parallel frame elements 54. The length adjustment members 60are configured to provide selective gripping between the lower frameelements 54 and the upper frame element 56, such that the overall lengthof the T-shaped upper pivoting assembly 50 may be varied as desired.

As shown in FIG. 10, the upper pivoting assembly 50 also includes anadjustable lateral force member 64 that includes a carriage 66, a paddedflange 67 and a fixing member 68. As will be discussed elsewhere in thisapplication, the carriage 66 allows for adjustment of the support member64 relative to the transverse member 62 to facilitate manipulation ofthe leg. The fixing member 68 fixes the carriage 66 relative to thetransverse member 62. Preferably, the longitudinal position of thelateral force member 64 is above the knee joint proximate the thighportion of the patient's leg as is generally shown in FIG. 2A and 2B.

In a preferred embodiment, the lateral force member 64 is selectivelylocked in a position proximate the patient's leg and an inflatablebladder is positioned between the lateral force member 64 and the leg.The leg is urged away from the lateral force member 64 and into adesired alignment with the reference axis when the bladder is inflated,as will be discussed in greater detail later. Alternatively, a force maybe applied to the lateral force member 64 in an axis parallel to thetransverse member 62 and in the direction of the leg. This force willurge the leg is into a desired alignment with the reference axis aftercontact is made. At this point, the lateral force member may beselectively locked in place.

The upper pivoting assembly 50 also includes a support column 70 thatextends from one end of the transverse member 62. Supported by thesupport column 70 is a cutting guide mounting assembly 71. This assembly71 includes a cross member 72, an adjustment bracket 73, and a cuttingguide mounting member 74. The cutting guide mounting member 74 will bediscussed in more detail elsewhere in this application, as it provides amounting structure for a cutting guide that aids the surgeon is cuttingthe femur and tibia in a desired axis and contour relative to thepreferred mechanical axis.

Lower Pivoting Member 80

Referring to FIG. 9, the lower pivoting member 80 has one end pivotablyattached to the upper pivoting assembly 50 at pivot point P2 and has anopposite end attached relative to a carriage 90 at pivot point P3. Thelower pivoting member 80 could be considered “H-shaped,” in that itincludes two parallel frame members 81 and a connecting cross member 82.

The lower pivoting members 80 are pivotably attached relative to thecarriage 90 at pivot point P3. This carriage 90 is slidably mountedalong the longitudinal axis of the spine member 22 of the stationarybase 20. Alternatively, a ball bearing construction could be used asillustrated by the exemplary ball bearing 91 As may be understood, asthe carriage 90 moves along the length of the spine member 22, apivoting action is provided between the upper pivoting assembly 50 andthe lower pivoting member 80, such as is illustrated by reference to thepositions shown in FIGS. 4 and 5. This allows the leg positioned thereonto be bent to a greater or lesser degree as desired.

Foot Support Assembly 130

Returning to FIGS. 4 and 5, the foot support assembly 130 is adjustablyattached relative to the spine member 22, such that it can be slidrelative to, yet fixed to, the spine member 22 as desired. The footsupport assembly 130 includes a carriage 132, a fixing member 134, apivot pin 135, and a foot cradle assembly 136.

The carriage 132 provides a sliding action intermediate the foot supportassembly 130 and the spine member 22. The fixing member 134 provides afixing feature to fix the carriage 132 relative to the spine member 22.

Turning to FIG. 12, the foot cradle assembly 136 is configured to accepta foot of a patient (not shown) and includes a retention strap 138configured to retain the foot as and an attachment bracket 140. Theattachment bracket 140 is configured to engage a pivot pin 135 on thecarriage 132 such that a pivoting action is provided. By using a hookconfiguration, retention of the foot is provided while still allowingthe foot to rotate about the axis of the pivot pin 135 when the leg ismoved from its extended to its bent position. Furthermore, thisattachment means also facilitates the application of a force on the legof the patient along the axis of the spine away from the torso of thepatient in order to stretch the knee joint ligaments and distract theknee joint.

Bladder Assembly 160

Working in conjunction with the rigid elements described above, abladder assembly 160 provides a force to position a patient's leg intoalignment as shown in FIGS. 3A and 3B.

Turning to FIG. 14, the bladder assembly 160 generally includes abladder 162, a retention sleeve 163, a tube 164, a bulb 165 and a valve166. The bladder 162 is generally rectangular with the retention sleeve163 attached thereto. The retention sleeve 163 is configured to slideover the padded flange 67 or attach to the support column 70. The tube164 provides fluid communication between the bladder 162 and the bulb165. Valve 166 controls the flow of air into and out of the bulb 165. Asone of skill in the art will recognize, to inflate the bladder 162, thevalve 166 is adjusted to allow air to flow in one direction into thebulb 165. As the bulb 165 is squeeze and released, air is forced intothe bladder 162. To deflate the bladder 162, the valve 166 is adjustedto allow air to escape. The selective inflation and deflation of thebladder 162 allows the surgeon to position the patient's leg as desired.

Method of Operation

As previously described, the present invention is generally used toposition a patient's leg into a desired alignment for surgery and/ortreatment of the knee joint. The following paragraphs will describe themethod of operation for an embodiment of the present invention.

With reference to FIG. 15, the process begins at Step 200 where an X-rayof the patient is taken to determine the distance from a skeletalreference point to the femoral head of the leg requiring treatment.Preferably, the skeletal reference point is the anterior superior iliacspine.

Meanwhile, the apparatus 10 is placed on a substantially horizontalsupport surface such as the floor, a hospital bed or table at Step 210.Preferably, the weight of the patient will secure the device to thesupport surface. Alternatively, the device may be secured to the supportsurface with attachment brackets, straps or any other method of securingknown in the art. The pelvic location assembly 30 is secured to theplanar head 21 of the stationary base 20 on the side corresponding withthe leg to be treated using securing member 25 and locating pins 24. Inother words, if the right leg of the patent is being treated, the pelviclocation assembly 30 is secured to the right side of the planar head 21.Then, the skeletal location bar 36 is adjusted according to the distancemeasurement from Step 200 using the scale located thereon.

At Step 220, the patient is positioned with his posterior on planar head21 of the stationary base 20. The leg to be treated is positionedsubstantially parallel to the spine member 22 and between the adjustablelateral force member 64 and the support column 70. The patient ispositioned such that the skeletal reference point on the patient's bodyis positioned proximate the skeletal locator 38. The upper pivotingassembly 50 is adjusted along its length such that the pivot axis PA2 ispositioned proximate the knee of the patient.

The foot support assembly 130 is moved along the spine member 22 toallow the patient's foot 8 to be position therein. The patient's foot 8is secured to the foot cradle assembly 136 using retention strap 138.The knee joint is then placed in tension by exerting a force on the footsupport assembly 130 in a direction away from the patient's torso alongthe axis of the spine 22 and the foot cradle assembly 136 is secured tothe spine member 22. This tension preferably extends the knee ligamentsto their maximum length. At this point, the setup of the apparatus iscomplete and ready for determining the proper mechanical axis MA of thepatient's leg 5.

At Step 230, the proper mechanical axis of a human leg is determined. Toestablish a reference axis within substantially the same vertical planeof the mechanical axis of the patient's leg, the elongate member 41 ispivoted towards the body and stops parallel with the skeletal referencelocation bar 36. Because the patient is positioned with the skeletalreference locator 38 proximate the skeletal reference point, thealignment reel 42 at the end of the elongate member 41 is locatedproximate the center of the femoral head of the leg receiving treatmentwhen rotated into place. The alignment line 43 is then extended from thealignment reel 42 to the foot cradle assembly 136 to provide a visualindication of the reference axis. This reference is substantially withinthe same plane as the mechanical axis MA for the patient.

After identifying the proper mechanical axis MA for the patient's leg 5,the leg 5 is urged into a desired alignment with this visual axis atStep 240. To accomplish this alignment, a bladder assembly 160 ispositioned on the lateral force member 64 and the support column 70. Thebladder assemblies 160 are selectively inflated and contact a portion ofthe leg above the knee and proximate the thigh. The selective inflationurges the leg into alignment with reference axis and therefore into adesired alignment with the mechanical axis. Preferably, the patient'sleg is positioned in a desired alignment with the reference axis whenthe reference axis is slightly to the medial side of the knee portion ofthe leg. At this step in the process, the leg is held in the propermechanical axis as indicated by the reference axis established in Step230. After the leg is secured in the proper mechanical axis by theexternal framework, the alignment line 43 may be retracted into thealignment reel 42 and the surgical procedure and/or treatment may begin.

As discussed earlier in this application, a typical surgical procedureon the knee joint is the application of a prosthesis for all or aportion of the bearing surfaces. To accommodate a prosthesis, all or aportion of the bearing surfaces of the femur and tibia must be removedas shown in FIG. 1.

Unicompartmental knee or partial replacement requires that a portion ofthe medial tibia and the medial femoral condyle be removed toaccommodate the new bearing surface. The cuts in the end of the tibiaand the end of the femur are preferably perpendicular to the mechanicalaxis and thus necessarily parallel to each other when the knee is infull extension. Further cuts in the end of the femur may be necessary toaccommodate the typically curved femoral bearing surface or femoralprosthesis which is typically made from metal but could be fashionedfrom other materials including human tissue. With a unicompartmentalknee replacement there is always a saggital or side cut which extendsfrom the usual planar cut at the end of the bone into the joint suchthat only half of the distal femur and half of the proximal tibia iscut.

The Total Knee Replacement requires that the entire proximal tibia andthe entire distal femur be cut in order to accommodate for the newtibial and femoral bearing surface or prosthesis. Again there may benecessary cuts in the femur to bevel the end of the femur to accommodatefor a bearing surface or prosthesis that is curved in nature. Certainly,the cutting guide mounting assembly 71 could accommodate other cuttingguides for removal of small portions of the joint for smaller or partialsurface bearing replacements to occur.

Before making any cuts to the bone, the surgeon will determine theamount of clearance in the joint needed for proper operation of theprosthesis. At Step 250, the clearance between the femur and the tibiaof an undamaged portion of the knee is measured using the measurementtool 150. If the surfaces of the knee requiring treatment are damagedfor example for a total knee replacement, the surgeon may measure thespacing in the other knee to use as a reference.

To check the “play” in the knee joint, the patient is positioned in theapparatus 10 with the leg receiving treatment aligned with the propermechanical axis and distracted. The measurement tool 150 is positionedbetween the bearing surfaces of the femur and tibia to determine thedistance between the bearing surfaces. From this measurement, thesurgeon can calculate the amount of bone that needs to be removed fromthe ends of the femur and tibia for proper positioning of theprosthesis. This calculation includes the space required by theprosthesis plus the distance measured between the bearing surfaces. Forexample if one millimeter of joint clearance is desired and the overallthickness of the prosthesis is twenty millimeters, then ten millimetersof tibia and eleven millimeters of femur will be is removed to achievethe desired 1 mm clearance.

To assist the surgeon in determining the proper amount of bone toremove, a spacer having the thickness of the desired joint play may beinserted between the bearing surfaces of the prosthesis joint. Usingthis technique, the surgeon simply measures the prosthesis with thespacer in place to obtain the space necessary to receive the prosthesisand to create the optimum joint play. The spacer itself may be made of aconventional dissolvable material and attached to one of the bearingsurfaces of the prosthesis joint. In this embodiment, the desired jointplay will be present when the spacer dissolves shortly after thesurgery. Additionally, the dissolvable space may include an antibioticor other factors that release as the spacer is dissolved to promote thehealing of the knee. Alternatively, the spacer may be made of anon-dissolvable material such as metal or plastic and remove by thesurgeon after insertion of the prosthesis.

In preparation for removing bone, the cutting guide mounting member 74and the adjustment bracket 73 are adjusted to position cutting guidesproximate the proximal end of the tibia at Step 260. These cuttingguides are preferably held perpendicular to the mechanical axis MA. Acutting saw or routing tool is then used to remove the desired amount ofbone from the tibia. This procedure is repeated for the distal end ofthe femur.

After the cuts are made, the cut surfaces must be shaped to accept theprosthesis at Step 270. Typically this requires beveling the cutsurfaces of the bone. To accomplish this task, the leg is positioning bythe apparatus 10 in the bent condition. The fixing member 134 of thefoot support assembly 130 is release and the leg manipulation assembly40 is pivoted upwardly by directing a force at pivot point PP2 in anupward direction. This causes the foot support assembly 130 and thecarriage 90 to slide along the spine member 22 toward the patient'storso. After the desired degree of bend is achieved, the fixing member134 secures the foot cradle assembly 130 to the spine member 22 whilestill allowing the foot cradle assembly 130 to pivot relative the pivotpin 135. As may be understood, a bladder may be positioned under thethigh when the leg is in the bent position in order to providedistraction to the knee to allow for finishing cuts on the bone and/orinstallation of various prosthetic devices.

A conventional beveling tool is then used to shape the cut ends of thebone to accept the prosthesis. These tools typically use the cut surfaceas a guide for the beveling operation. After beveling and with the kneein a bent position, the prosthesis is positioned on the cut surfaces ofthe tibia and femur. The leg is then returned to a straight conditionand the ligaments of the knee compress the prosthesis.

Variations

As may be understood, the present invention contemplates variations inconfiguration and use. For example, instead of using bladders toposition the knee, a force may be applied directly to the adjustablelateral force member 64 and therefore onto the leg until the leg is inalignment with the proper mechanical axis MA. In this embodiment,lateral force members 64 are slideably attached to transverse member 62such that the patient's leg would be positioned between the two supportmembers 64. Referring briefly to FIG. 3A, the two padded flanges 67 areplaced against the medial and lateral aspect of the distal femur. Usingthese two padded flanges the knee is pushed or pulled such that the legis urged into alignment with its proper mechanical axis MA. Each flangeis then locked into place on the transverse member 62 using fixingmembers 68. This assures that the knee will remain in the patient'soptimal mechanical position. It also allows the cross member 72 of theapparatus 10 to remain in a plane perpendicular to the patient's kneeallowing surgical cuts to be made accurately with respect to themechanical axis MA. Additionally, during the surgical procedure,conventional skin and/or soft tissue retractors can be attached to thesemedial and lateral pads to allow easy and assistant-free access to theinside of the knee.

In a further variation, a routing tool may be to the external frameinstead of cutting guides as described elsewhere in this application. Inthis embodiment, the knee is positioned in the apparatus 10 such thatthe leg is fully extended and aligned with the mechanical axis asdescribed above. Once the knee is properly aligned in the device, anoperating arm supporting the routing tool is attached to the supportcolumn 70 such that the arm is fixed in a plane perpendicular to themechanical axis MA and lies anterior to the knee. This operating arm canbe moved superiorly and inferiorly along the MA. It can also moveanterior and posterior relative to the knee. During these movements, thearm preferably remains perpendicular to the MA of the leg.

Generally, a “flat walled” drill or router bit is used which has asubstantially round and constant cutting circumference. By rotating therouter bit about its longitudinal axis and moving it along an axisperpendicular to its rotational axis, a flat wall may be formed on thebone if the router is drawn past an uneven surface.

An end and side cutting bit attached to a high speed drill or router canbe attached to the operating arm such that it can slide medial andlateral along the line of the arm. When the drill is lowered to a bonein the knee and the drill is moved along the operating arm medial andlateral, the end and side cutting bit will create a flat surface cut inthe bone along the plane that is perpendicular to the mechanical axis.As the bit is lowered more and more posteriorly the bone can be cut intwo leaving the end of the bone perfectly flat with a surface that isperpendicular to the MA. Thus, when the patient is standing the flat cutat the end of the tibia and the end of the femur will be generallyparallel to the floor.

As an alternative, the routing tool could be made to rotate about afixed position on the operating arm thereby creating a cutting arc whichis preferably perpendicular to the MA.

Typically, the tibia is cut first followed by the femur. The exactdistance between the distal femoral cut and the proximal tibia cutshould equal the thickness of the knee prosthesis to be inserted plusthe amount of normal play desired in the joint.

Once the end of the femur is cut in the above fashion it must be shapedto fit the prosthesis. In the apparatus 10, the femur is lifted up andthe knee bent and rigidly fixed. Once in this position, the foot supportassembly 130 is secured to the spine member 22. A bladder is inflatedunderneath the thigh such that the thigh is moved away from the upperpivoting assembly causing the femur to be lifted away from the proximaltibia. This creates a distraction force that lifts the end of the femuroff of the tibia.

Once the knee is bent and distracted, the cut ends of the femur andtibia can be shaped or a secondary cut made so the cut surfaces of thebone conform to the mating surfaces of the prosthesis. For example, anend and side cutting bit can be positioned in a routing tool to createthe necessary flat surfaces relative to the original cut surface of thefemur for any and all varieties of knee prosthesis.

In some situations, a patient may not be able to extend the kneecompletely, resulting in a condition known as “flexion contracture.”Assuming that the knee has a 10 degree bend in it, the surgeon canbisect the remaining bend and pivot the router about the operation arm 5degrees in order to provide a cut on the tibia. Typically the leg willthen fall into a straight position and the surgeon can continue asdescribed elsewhere. The initial cut to the tibia can, if needed, berevisited and re-cut if needed.

In addition to total or unicompartmental knee arthoplasty, the presentinvention may be used in an osteotomy procedure which is performed tocorrect a varus or valgus deficiency. With reference to FIG. 16, aconventional osteotomy procedure includes removing a wedge portion 304from the tibia 300 at a location space apart from the bearing portion302 of the tibia 300. After the wedge portion is removed, the bearingportion 302 is reattached to the remaining tibia 300 using a metal plateand screws. To facilitate the proper wedge shape, a cutting guideproviding a wedged shaped template as shown in FIG. 17A may bepositioned using an embodiment of the present invention.

In addition to the wedge shaped cut, domed or arcuate cut osteotomyprocedures have been performed, but with limited success due to thedifficulty in achieving an arcuate cut manually. An embodiment of thepresent invention provides a cutting guide with an arcuate slot as shownin FIG. 17B and an external frame to position the cutting guide toimprove the accuracy of the domed or arcuate cut.

In the domed cut osteotomy, an arcuate cut 321 is made in tibia 320 asbest shown in FIG. 18. The bearing surface portion 322 of the tibia 321is then rotated into the desired location. To secure the two portions ofthe tibia in a desire location, a retention rod 330 is used.

Referring to FIG. 19, the retention rod is a generally “T” shaped memberhaving a transverse head portion 331 and an elongate portion 332. Thetransverse portion 331 is configured to accept convention fasteners. Theelongate portion 332 includes a plurality of slots 333 configured toaccept convention fasteners while still allowing movement in a directionparallel with the elongate axis of the retention rod 330. As one ofordinary skill in the art will appreciate, any number of fasteners maybe used to secure the rod 330 to the bone. Furthermore, the rod shapemay be formed to follow more closely the contour of the bone as desired.

After the two portions of the tibia are positioned in a desiredlocation, the elongate portion of the retention rod 330 is partiallyinserted into the tibia as generally shown by dashed lines in FIG. 18.Fasteners 336 are driven into the tibia 320 and through the slots 333 tosecure the retention rod 330 to the tibia 320 while still allowingmovement of the rod in its longitudinal axis. The bearing surfaceportion 322 of the tibia 320 is secured to the head portion 331 of theretention rod 330 using convention fasteners.

The domed cut osteotomy procedure is beneficial because there is minimalloss in tibia length and there is greater surface contact area forhealing than with the wedge cut procedure. Furthermore, the retentionrod attachment discourages relative movement of the tibia 320 and thebearing surface portion 322 both rotationally and laterally in a planeperpendicular to the longitudinal axis of the rod. However, thisattachment method allows some movement in the axis parallel to theretention rod 332 due to the use of slots 333 to attach the rod to thetibia 320.

Adjustments

The present invention has several adjustments to accommodate a varietyof patient sizes and shapes. During the initial setup, the foot cradleassembly 130 may be adjusted along the length of the spine member 22 toaccommodate varying leg lengths. Similarly, the length of the upperpivoting assembly 50 may be adjusted to position the pivot point PP2under the knee. This allows the invention to accommodate patients withdifferent femur lengths.

The pelvic location assembly 30 also provides adjustments for varyingwaist measurements. As discussed earlier in this application, theadjustable frame member 34 allows for vertical adjustment of theskeletal reference location bar 36 along the length of the verticalsupport member 32 to accommodate girth variations between patients.

The present invention also includes provisions for adjusting thelocation of cutting guides. These provisions include a verticaladjustment of the cutting tool mounting assembly 71 that allows thesurgeon to position the guides at a desired distance above the kneejoint. The cutting guide mount assembly 74 itself also providesadjustments laterally (i.e. perpendicular to the elongate axis of theleg) and longitudinally (i.e. parallel elongate axis of the leg)allowing the surgeon to position the guides as desired.

Additionally, the apparatus may be configured for use on either leg.This is accomplished by moving the pelvic location assembly 30 from oneside of the planar head 21 to the other. In other words, if the rightleg of the patent is being treated, the pelvic location assembly 30 issecured to the right side of the planar head 21.

To position the pelvic locating assembly 30, the present inventionprovides two locating pins 24 on each side of the planar head 21 as bestshown in FIG. 6. The pelvic location assembly is configured to acceptthe locating pins and provides a securing member 25 to retain the pelvislocation assembly 30 to the planar head 21 of the stationary base 20.

1. An apparatus for identifying the mechanical axis of a leg of apatient to facilitate medical treatment thereon, said leg including afemoral head, and a foot portion which itself includes an ankle portion,said mechanical axis having a portion extending from the center of saidfemoral head to the center of said ankle, said apparatus comprising: abase member including a spine portion and a head portion, said spineportion being substantially elongate and having a longitudinal axis,said head portion attached proximate one longitudinal end of said spineportion; a pelvic location assembly attached relative to said basemember proximate said head portion, said pelvic location assemblyincluding a femoral head location member configured to establish a firstreference point positioned at a known location relative to the center ofsaid femoral head; a carriage moveably attached relative to said spineportion and configured to be moved along a carriage path having aportion being substantially parallel to said longitudinal axis of saidspine, said carriage further configured to be selectively securedrelative to said spine so as to discourage said relative movementbetween said carriage and said spine; a boot assembly pivotably attachedrelative to said carriage and configured to accept said foot portion ofsaid leg and to establish a second reference point at a known locationrelative to the center of said ankle portion; and a mechanical axisindicator providing a visual indication of a portion of a reference axispassing from said first reference point to said second reference point,said reference axis is within substantially the same plane as saidmechanical axis.
 2. The apparatus of claim 1, wherein said mechanicalaxis indicator comprises a retractable wire configured to have a freeend attachable to said boot assembly at a location proximate said secondreference point.
 3. The apparatus of claim 1, wherein said mechanicalaxis indicator comprises a visible laser.
 4. The apparatus of claim 1,wherein said moveable attachment is a sliding attachment allowing saidcarriage to slide relative to said spine portion such that the kneebends.
 5. The apparatus of claim 1, wherein said moveable attachment isa rolling attachment allowing said carriage to roll relative to saidspine portion such that the knee bends.
 6. The apparatus of claim 1,wherein said base member defines a support surface for the posterior ofsaid patient that is substantially horizontal, and wherein said planecontaining said reference axis and said mechanical axis is substantiallyvertical.
 7. The apparatus of claim 1, wherein said carriage includes apin oriented in a plane perpendicular to said longitudinal axis of saidspine portion, and wherein said boot assembly includes an attachmentbracket with a hook portion that is configured to engage said pin onsaid carriage such that said boot assembly pivots as said carriage movesrelative to said spine portion.
 8. An apparatus for aligning a leg of apatient with a mechanical axis to facilitate medical treatment thereon,said leg including a femoral head, a thigh portion and a foot portionwhich itself includes an ankle portion, said mechanical axis having aportion extending from the center of said femoral head to the center ofsaid ankle, said apparatus comprising: a base member including a spineportion and a head portion, said spine portion being substantiallyelongate and having a longitudinal axis, said head portion attachedproximate one longitudinal end of said spine portion; a pelvic locationassembly attached relative to said base member proximate said headportion, said pelvic location assembly including a femoral head locationmember configured to establish a first reference point positioned at aknown location relative to the center of said femoral head; a carriagemoveably attached relative to said spine portion and configured to bemoved along a carriage path having a portion being substantiallyparallel to said longitudinal axis of said spine, said carriage furtherconfigured to be selectively secured relative to said spine so as todiscourage said relative movement between said carriage and said spine;a boot assembly pivotably attached relative to said carriage andconfigured to accept said foot portion of said leg and to establish asecond reference point at a known location relative to the center ofsaid ankle portion; a mechanical axis indicator providing a visualindication of a portion of a reference axis passing from said firstreference point to said second reference point, such that said referenceaxis is within substantially the same plane as said mechanical axis; anda leg manipulation assembly attached relative to said spine portionbetween said pelvic location assembly and said boot assembly, said legmanipulating assembly having a first lateral force assembly and a secondlateral force assembly said force assemblies being proximate said thighportion and spaced apart to accept said leg therebetween, said firstlateral force assembly being adjustable and selectably securable alongan axis substantially perpendicular to said longitudinal axis of saidspine and configured to discourage said leg from moving away from adesired alignment with said mechanical axis identifier.
 9. The apparatusof claim 8, wherein said first lateral force assembly includes a firstpost member and a first inflatable bladder, said first inflatablebladder being positioned between said first post member and said legsuch that inflation of said first bladder tends to cause said firstbladder to bias against said leg proximate said knee such that said kneetends to move away from said first post member; wherein said secondlateral force assembly includes a second post member and a secondinflatable bladder, said second inflatable bladder being positionedbetween said second post member and said leg such that inflation of saidsecond bladder tends to cause said second bladder to bias against saidleg proximate said knee such that said knee tends to move away from saidsecond post; and wherein said first and second bladders are configuredsuch that selectively inflating said first and said second bladderstends to provide a bias between said leg proximate said thigh portionand at least one of said first and said second bladders, thus urgingsaid knee into a desired alignment with said mechanical axis identifier.10. The apparatus of claim 9, wherein selectively inflating said firstand said second bladders discourages movement of said leg relative tosaid first and said second post members.
 11. The apparatus of claim 8,wherein said first lateral force assembly includes a first force membermoveably attached relative to said base member such that said first postmember is adjustable and selectively securable in an axis substantiallyperpendicular to the longitudinal axis of said spine portion; whereinsaid second lateral force assembly includes a second post membermoveably attached relative to said base member such that said secondforce member is adjustable and selectively securable in an axissubstantially perpendicular to the longitudinal axis of said spineportion and spaced apart from said first post member to accept said legtherebetween; and wherein further said force members contact said legand urge said knee into alignment with said mechanical axis identifier.12. The apparatus of claim 8 further comprising a cutting guide mountingassembly attached relative to said first post and configured to positiona cutting guide proximate a knee portion of said leg.
 13. The apparatusof claim 12, wherein said cutting guide mounting assembly is adjustablein at least two orthogonal axes.
 14. The apparatus of claim 12, whereinsaid cutting guide mounting assembly is configured to facilitate boneremoval in an axis perpendicular to said mechanical axis.
 15. Theapparatus of claim 8 further comprising an operating arm configured tosecure a cutting tool and to provide movement of said cutting tool in atleast two axes.
 16. The apparatus of claim 15, wherein said operatingarm is configured to pivotably secure said cutting tool, wherein furthersaid cutting tool pivots about an axis substantially parallel to saidlongitudinal axis of said spine portion.
 17. An apparatus for aligning aleg of a patient with a mechanical axis to facilitate medical treatmentthereon, said leg including a femoral head, a thigh portion, a kneeportion and a foot portion which itself includes an ankle portion, saidmechanical axis having a portion extending from the center of saidfemoral head to the center of said ankle, said apparatus comprising: abase member including a spine portion and a head portion, said spineportion being substantially elongate and having a longitudinal axis,said head portion attached proximate one longitudinal end of said spineportion; a pelvic location assembly attached relative to said basemember proximate said head portion, said pelvic location assemblyincluding a femoral head location member configured to establish a firstreference point positioned at a known location relative to the center ofsaid femoral head; a carriage moveably attached relative to said spineportion and configured to move along a carriage path having a portionbeing substantially parallel to said longitudinal axis of said spine andfurther configured to be selectively secured relative to said spine soas to discourage said movement; a boot assembly pivotably attachedrelative to said carriage and configured to accept said foot portion ofsaid leg and to establish a second reference point at a known locationrelative to the center of said ankle portion; a upper pivoting assemblyhaving a first end pivotably attached relative to said spine portionproximate said head portion, a second end pivotably and moveablyattached relative to said spine portion and a hinged portion positionedproximate said patient's knee between said first end and said second endsuch that when said patient's knee is in a bent condition, said secondend moves relative to said spine portion and said hinge portion followssaid knee such that said thigh support member also provides support tosaid thigh portion of said leg; a mechanical axis indicator providing avisual indication of a reference axis passing through said firstreference point and through said second reference point, such that saidreference axis is within substantially the same plane as said mechanicalaxis; and a leg manipulation assembly attached relative to said spineportion between said pelvic location assembly and said boot assembly,said manipulating assembly having a first lateral force assembly and asecond lateral force assembly being spaced apart to accept said legtherebetween and located proximate said knee joint, said first lateralforce assembly being adjustable and selectably securable in an axissubstantially perpendicular to said longitudinal axis of said spine andconfigured to urge said leg into alignment with said mechanical axisidentifier.
 18. The apparatus of claim 17, wherein said thigh support isconfigured to allow free movement of a calf portion of said leg whensaid leg is in said bent condition.
 19. The apparatus of claim 17further comprising an inflatable bladder positioned intermediate saidthigh portion and said upper pivoting assembly to encourage distractionof said knee joint when knee is in a bent condition and said bladder isselectively inflated.
 20. The apparatus of claim 17 further comprising acutting guide mounting assembly attached relative to said first post andconfigured to position a cutting guide proximate a knee portion of saidleg.
 21. The apparatus of claim 20, wherein said cutting guide mountingassembly is adjustable in at least two orthogonal axes.
 22. Theapparatus of claim 20, wherein said cutting guide mounting assembly isconfigured to facilitate bone removal in an axis perpendicular to saidmechanical axis.
 23. The apparatus of claim 20, wherein said cuttingguide includes an arcuate slot configured to provide a path for a bonecutting tool to follow.
 24. The apparatus of claim 20, wherein saidcutting guide includes a wedge shaped slot configured to provide a pathfor a bone cutting tool to follow.
 25. A method for preparing apatient's leg having a femur with a femoral head, a thigh portion, aknee portion, a femur, a tibia, and an ankle portion, for treatmentthereon, said method comprising the steps of: providing a firstreference point proximate said femoral head; providing a secondreference point proximate the center of said ankle portion; andproviding a visual indication of a reference axis passing from saidfirst reference point to said second reference point such that saidvisual indication is within substantially the same plane as themechanical axis of said leg, said mechanical axis having a portionextending from the center of said femoral head to the center of saidankle.
 26. The method of claim 25, wherein said step of providing afirst reference point comprises the steps of: taking an Xray of saidpatient showing at least the location of a skeletal reference and saidfemoral head; identifying said skeletal reference on said patient; andpositioning said first reference point proximate said femoral head ofsaid patient responsive to said distance obtained from said Xray. 27.The method of claim 25 further comprising the steps of: urging said leginto a desired alignment with said reference axis; and providing anexternal frame configured to secure said leg in said desired alignment.28. The method of claim 25 further comprising the steps of: providing acutting guide mounting assembly attached relative to said external frameand configured to position a cutting tool proximate to said knee joint;removing at least a portion of the distal end of said femur; andremoving at least a portion of the proximal end of said tibia.
 29. Themethod of claim 28 further comprising the steps of: providing an upperpivoting assembly configured to support said leg proximate said thighand having an inflatable bladder positioned intermediate said leg andsaid thigh support; positioning said leg in with said knee in a bentcondition such that said thigh support is positioned proximate saidthigh portion of said leg; and selectively inflating said bladder suchthat said thigh is urged away from said upper pivoting assembly tendingto cause distraction at the knee.
 30. The method of claim 28 furthercomprising the steps of: distracting said knee portion of said leg byapplying a force to said foot portion in a direction away from saidtorso of said patient in a direction substantially parallel to thelongitudinal axis of said leg; providing a wedged shaped measuring toolconfigured to contact the bearing surfaces of said femur and said tibiaat said knee portion and provide indicia of a clearance between saidbearing surfaces.
 31. The method of claim 30 further comprising thesteps of: providing a prosthesis assembly having a first memberconfigured to be secured to said femur of said leg, and a second memberconfigured to be secured to said tibia of said leg, each of said firstand second members having a bearing portion configured to cooperated toprovide movement at said knee portion. providing a dissolvable spacerbetween said bearing surfaces, said space having a thicknesssubstantially the same as said measured clearance.
 32. The method ofclaim 30, further comprising the step of releasing an antibiotic fromsaid spacer when said spacer dissolves.
 33. An apparatus configured tomeasure the clearance between the mating surfaces of the femur and atibia at the knee joint, said apparatus being elongate with asubstantially wedge shaped tip portion, said tip portion includingindicia associated with a width at a distance spaced apart from the endof said tip.